Members of ethnic/racial minority groups in the United States suffer worse health outcomes and are less satisfied with their health care than Whites, even after biological, socioeconomic and access factors are taken into account. Hypertension is one such health condition in which ethnic/racial disparities have been well documented. The assumption is often made that bias among healthcare providers contributes to these disparities, but the nature and operation of such bias has not been identified. In response to NHLBI PA-07-206, "The Effect of Racial and Ethnic Discrimination/Bias on Health Care Delivery," this project is designed to fill that gap by measuring providers'implicit (unconscious) and explicit (conscious) biases toward African Americans and Latinos, and examining the degree to which those biases are associated with disparities in hypertensive patients'perceptions, disease management, and health outcomes. Over a decade of basic research in social psychology has shown that implicit ethnic/racial biases can influence behavior, despite people's best intentions. The Implicit Association Test (IAT) has been extensively validated to measure these biases and will be administered, along with measures of explicit bias, to 300 primary care providers (PCPs) in three settings: a public safety-net delivery system, a large group-model HMO, and a network of private practices. A random sample of the PCPs'hypertensive patients, stratified by ethnicity/race, will then be surveyed and using a retrospective cohort design, their electronic administrative records will be analyzed over a 3-year observation period. The first Specific Aim of the project is to measure PCPs'implicit and explicit ethnic/racial attitudes, and compare them to the attitudes of people in the communities they serve. Specific Aims 2 and 3 focus on the associations between PCPs'implicit and explicit attitudes and differences between minority (Latino &African American) and White patients in the degree to which care is perceived as patient-centered (Aim 2), the appropriate intensification of hypertension treatment (Aim 3.1), appointment keeping and medication adherence (Aim 3.2), and blood pressure control (Aim 3.3). The project will provide a better understanding of the role that ethnic/racial biases play in health disparities and guide the development of interventions to combat bias. Implicit and explicit biases respond differently to intervention, thus their independent or combined roles in health disparities must be understood for the elimination of disparities to be achieved. Public Health Relevance: Uncontrolled hypertension is one of the most significant public health problems facing the United States today, and African Americans and Latinos carry a disproportionate burden of the disease. This project represents one of the first investigations of the degree to which ethnic/racial bias among healthcare providers is associated with disparities in the management and control of hypertension. By combining the theory and methods of social psychology with those of health outcomes research, this line of work represents an innovative approach to elucidating the causes of a serious public health problem.